Method of replacing tubes in heat exchangers



METRUD OF REPLACING TUBES IN HEAT EXGHANGERS Filed Feb. 14;; 1944 Z shee'ils -Sheet l Bnnentor HENRY G. MOORE.

attorney Oct 28, 1947. H. 5. MOORE 3 METHOD OF REPLACING'TUBES IN HEAT EXCHANGERS Filed Feb 14, 1944 s Sheets-Sheet 2 Imnentor HENRY G. Moo/v5.

Oct. 28, 1947..

H. MOORE METHOD OF REPLACING TUBES IN HEAT EXCHANGERS Filed Feb. 14, 1944 I 5 Sheets-Sheet 3 l'mventor HENRY G. MOORE.

Qttorueg Patented a. 2a, 1947 METHOD or REPLACING TUBES IN HEAT EXCHANGERS Henry G. Moore. Redondo Beach, Calif., assignor to The Garrett Corporation, Airesearch Manufacturing Company division,

Los Angeies,

021111., a corporation of California Application February 14, 1944, Serial No. 522,258

This invention relates to the making of emergency repairs to oil coolers such as are employed on aircraft or in other situations for reducing the temperature of circulating oil for cooling and lubricating motor parts, bearings, or other parts.

These coolers are usually formed of a bank of thin walled tubes, the heads of which are of polygonal form, the flat sides of which are soldered together. As weight is an important consideration in airplane construction, these tubes are necessarily very thin and are apt to spring a leak.

One of the objects of this invention is to provide a simple method and apparatus for removing a defective tube from a bank of tubes such as referred to above, and for effecting its replacement by a new tube.

Another object of the invention is to provide simple means for melting out the solder at the heads of the defective tube, preparatory to afiecting its removal from the bank.

A further object is to provide simple means for enabling the replacement tube to be treated at its ends so as to adapt it for carrying solder in its exterior preparatory to introducing it into the bank and soldering it there. In the preferred practice of the method this is accomplished by fluting or crimping the thin Wall of the replacement tube at its head so as to form grooves that are adapted to retain solder, and one of the objects of the invention is to provide simple means for accomplishing this, and for expanding and heating the heads of the replacement tube when inserted in the bank of tubes to solder .t to the heads of the tubes which surround it.

A further object of the invention is to provide a kit of simple tools for effecting the removal and replacement of a defective tube, and particularly to provide a heating tool having interchangeable parts for (a) melting out the solder of the defective tube, (b) heatin and simultaneously expanding the heads of the replacement tube when inserted in the bank, and (c) melting the solder that is applied to the heads of the replacement tube preparatory to soldering them into ,the tube bank.

A further object of the invention is to construct the tools so that the purposes of the tools can be accomplished with a minimum number of parts.

Further objects and advantages of the inventii a will appear in the following part of the spec ification.

The invention consists'ln the novel parts and combination of parts to be described hereinafter, all of which contribute to produce anove1 and 4 Claims. (Cl. 29-1574) efllcient method for replacing defective tubes in a bank of tubes. v

A preferred embodiment of the invention is described in the following part of the specification,

while the broad scope of the invention is pointed out in the appended claims.

In the drawings:

Fig. 1 is a side elevation of'a bank of cooler tubes removed from an oil cooler and illustrating the first step of my method in removing a defective tube from the bank.

Fig. 2 is a fragmentary view, and is an end elevation of a group of tubes located around the tube which is represented as being removed, and showing the tip of the solder heating tool in cross-section, on the line 2 -2 of Fig. 1.

Fig. 3 is a perspective view of one of the solder removing tools complete with its handle and heater body.

Fig. 4 is a side elevation and partial section of one of the tube removing tools shown in Figs. 1 and 3, and which is also used for upsetting the ends of the replacement tube to give it the polygonal form adapting it to fit in between the similarly shaped heads of the adjacent tubes.

Fig. 5 is an end elevation of a tool, or die, which I employ for crimping or fluting the walls of the replacement tube head to give it a form adapting it for carrying solder on its exterior, preparatory to soldering it into the tube bank. I v Fig. 6 is a longitudinal section through the die shown in Fig. 5, taken on the line 66 of that figure. This view also illustrates the end of the replacement tube about to be moved into the die, to flute its side walls.

Fig. 7 is a cross section through this die on the line 'i| of Fig. 6, but with the head of the re placement tube in the die.

Fig. 8 is an end view of the fluted head shown in full lines and indicating in dotted lines the polygonal form the head had before the same was fluted or crimped.

Fig. 9 is a perspective view illustrating the heater tool shown in Fig. 1, but representing the same attached to the handle or shank of a crucible orv cup for melting the solder which is to be heater tool carrying the setting tool, or solderingin tool, which heats the walls of the head of the replacement tube and the adjacent walls of surrounding tubes to melt the solder carried by the replacement tube head and afllx the same in the bank of tubes.

Fig. 13 is a side elevation of the body of the tube setting tool and showing a portion of it in cross section.

Fig. 14 i an elevation of the inner end of the tube setter, illustrated in Fig. 13.

Fig. 15 is a fragmentary view, illustrating one of the final steps of my method in which the setting tool is applied in the end of the replacement tube to expand its head from within, to its proper polygonal form; and showing the auxiliary heater stems of this tool, all in cross section as they lie within the adjacent heads of adjacent tubes in the bank.

In Fig. 1 I illustrate a bank I of tubes 2 such as are mounted in an oil cooler. The tube 2a is indicated in the process of being removed from the bank of tubes and is supposed to be a defective tube. These tubes have upset heads 3 of polygonal form such as hexagon shaped, as shown, the side faces 4 of these heads being soldered tightly as indicated in Fig. 2.

In practicing my invention, I heat the heads 4 of the defective tube 2a from the inside by means of two tools 5 which are substantially alike, each tool including a holder 6 with a socket I extending in from its forward end; in this socket is held a hexagonal stem 8 that is adapted to fit snugly into the hexagonal mouth in the head 4 of the tube 2a.

The shank 9 of this stem 8 fits snugly into the socket 1 and is held therein by a set screw ill in the side of the body, the tip of which seats in a depression or flat pressed into the side of the shank. Such stem 8 has a round pilot tip ll of reduced diameter that extends into the base of the tube adjacent its hexagonal mouth.

Before applying the heating stems 8 in the mouths of the defective tube 2a, the body 6, which is of heat conductive material such as metal (preferably aluminum if the tool kit is to be used aboard an aircraft), is placed in a heating socket I 2 in the forward end of a heater I3 which in the present instance is an electric heater heated by a heater element l4, indicated diagrammatically in Fig. 1, and provided with a heat insulated handle through which the electric cord I6 is carried, which energizes the heater element 14. A collar lBa of insulating material may be employed for performing the function of insulating the handle.

As soon as the stems B are hot enough, they are inserted in the mouths of the defective tube and held there long enough to melt the solder, securing its heads. By exerting a thrust force in either direction against the tube 2a, it will shift out of line as soon as the solder is softened by the heat.

The next step of the method is to insert a replacement tube in the vacant space, occasioned in the bank by the removal of the defective tube. If desired, preformed space tubes interchangeable with the tubes in the bank can be carried in stock ready for use, in which case the tube ends are first thoroughly cleaned to remove any grease or other foreign matter which might interfere with the proper action of the solder-when setting the new tube in place.

In accordance with my method, I prepare the hex heads I! so as to enable them to. carry solder on their outer sides, (see Fig. 6) and this is preferably accomplished by crimping or grooving their flat side walls by means of a die I8. This die has a hexagonal socket l9 capable of receiving the hex head and, although in the present instance the hexagon socket is not tapered, I do provide the die with six small pins 20 which are mounted tightly in sockets 2| which are drilled in through the end face of the die so that the inner ends of the pins extend into through the facets of the hexagon socket, so that when the hex head of the tube is jammed forcibly into the socket, these pins will form longitudinally extending recesses or groove 22 that have their greatest depth at the extreme end of the head and run out to the fiat near the shoulder 23 of the hex head.

Solder is now applied to the exterior of the hex heads in any suitable manner. In the present drawing, this is accomplished by dipping the heads in a bath of solder 24, and, if desired, this solder may be melted in a crucible or cup 25 (see Fig. 10) which may be heated in the same heating tool l3, illustrated in Fig. 3. For this purpose, the cup may be provided with a shank 2B which fits interchangeably into the aforesaid socket l2.

When the hexagon heads I! are dipped, of course solder adheres to them in the grooves 22. This solder is permitted to harden sufliciently to prevent its being easily brushed ofi, after which the replacement tube 2b is inserted in the tube bank, see Fig. 11.

After the tube 2b is in place in the bank I, with its heads in the hexagonal sockets at the ends of the bank, then I apply heat within its hex mouths and expand its fluted sides out into firm .contact with the adjacent flat faces of the hex heads of adjacent tubes of the bank. For this purpose I prefer to employ a tube setting tool 21, illustrated in Figs. 12 to 14 inclusive, and preferably including a body or stem carrier 28 having a centrally disposed main stem 29 with a shank 30 socketed into the end of the body and secured there by a set screw 3| mounted like the aforesaid set screw l0. Disposed circumferentially around this main stem 29, the body carries a plurality of auxiliary stems 32. As illustrated, I employ three of these auxiliary stems, all of which are socketed in the body 28 like the main stem. In fact, all of these stems are of hexagonal form and disposed with their adjacent flat sides parallel to each other with a narrow flat gap 33 between the main stem and the other stems. This flat gap has a width'slightly greater than the thickness of any two adjacent flat walls of the heads 4.

Two of these setting tools 21 are employed, one at each end of the newly inserted tube with the main stem 29 socketed into the hex mouth of the new tube, and with the auxiliary stems 32 received in three adjacent tubes in the bank (see Fig. 15). The main stem 29 has a round pilot tip 34 which sockets itself in the base of the new tube 2b and it has a tapered shoulder 35 which cooperates with the hexagonal part of this stem to expand the fluted head I! of the new tube, thereby pushing its fiat sides out against the fiat sides of the adjacent hex heads of the tubes in the bank. At the same time heat is applied by heating the body 28, which, preferably. fits interchangeably into the socket [2 of the heater l3 (see Fig. 12). In this way all the stems 32 and the stem 29 are heated to melt the solder while their flat side faces exert pressure on the inner sides of the flat walls of the heads that are involved in the soldering operation.

When the setting has rested a sufficient time in this position, it is withdrawn, and is then oriented on the axis of its main stem 29, through 30 and is then reinserted so that the auxiliary stems 32 will now pass into the mouths 36 of the three tubes that lie between those that have just been penetrated by the auxiliary stems 32. In. this way the melting of the solder and setting of the same is completed to aflix the headsof the newly inserted tube into the bank.

Of course, if desired, the setting tool 21 could be provided with six auxiliary stems 32 instead of three, which would avoid the necessity of reinserting the setting tool. But I prefer to use only three auxiliary stems because when six are used, there is danger of overheating the bank of tubes so as to melt some of the solder where not intended. I

In the original bank of tubes their hex heads may be brazed together in which case a slightly greater amount of heating might be required to free a defective tube.

In using the settin tool 21 there may be a tendency for it to become stuck or frozen into the tube ends. For this reason, I may provide the sides of its body 28 with a plurality of circumferentially spaced sockets 31. These sockets enable a special tool to be applied for exerting considerable force on the tool to withdraw it.

The auxiliary stems 32 are preferably provided with pilot tips 32a of reduced diameter which assist in guiding their stems into their corresponding tubes when using the tool 21.

In an emergency, if no spare tubes with preformed hex heads are available, the setting tool 21 can be used to upset and form a length of tubing of proper length, as the walls of this tubing would be thin enough to permit this to be accomplished.

Many other embodiments of this invention may be employed without departing from the spirit of the invention.

I claim as my invention:

1. A method of replacing a defective tube in-a bank of tubes having polygonal heads, the sides 01' which adhere to each other, which consists in: removing the defective tube; forming polygonal heads on the ends of a piece of tube substantially the same length as the said bank; pressing grooves into the outer face of the wall of the said polygonal heads; applying solder in the said grooves; inserting the replacement tube in the bank with its heads in alignment with the other heads of tubes in the bank; expanding the poly onal heads into contact with the side faces of the faces of the heads of adjacent tubes in the bank: and simultaneously applying heat to enable the applied solder to amx the heads or the replaced tube in the bank.

2. A method according to claim 1, in which the expansion of the heads is effected by stages, in I polygonal heads of adjacent tubes of .the bank.

- 3. A method of replacing a defective tube in a bank of tubes having polygonal form heads affixed to each other, which consists in: forming like-shaped polygonal heads on the replacement tube; pressing the wall of said last named heads into substantially star-form; dipping the starformed heads into a bath of molten solder to lodge solder in the grooves on the outer side of the star-form heads; inserting the replacement tube in the tube bank with the star-form heads adjacent to the polygonal heads of the banked tubes; and then expandin the star-form heads of the replaced tube, with heat simultaneously applied to affix the same through the agency of the solder.

4. .A method of replacing a defective tube from a bank of tubes having heads soldered together, which consists in: inserting heating tools in the heads of the defective tube to melt its solder and facilitate shifting the defective tube out of the bank; forming heads on the replacement tube with crimped side walls so as to present exterior grooves thereon; placing solder in said grooves and permitting the same to cool in said grooves; inserting the replacement tube in the bank; expanding the crimped heads; and heating the same to enable the solder carried thereby to affix the same to the Walls of adjacent tube heads in the bank.

- HENRY G. MOORE.

REFERENCES crrsn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number v Name Date 2,209,975 Jacobus Aug. 6, 1940 920,743 Hines May 4, 1909 2,007,000 Oakey July 2, 1935 2,372,946 Foster et a1 Apr. 3, 1945 560,919 O'Toole May 26, 1896 1,857,912 Jones May 10, 1932 2,343,402 Clifiord Mar 7, 1944 1,964,051 Gordon et a] June 26, 1934 2,313,315 Blais Mar. 9, 1943 1,078,583 Johnson Nov. 11, 1913 2,200,528 Armstrong May 14, 1940 I 2,069,524 Gordon et al. Feb. 2, 1937 2,159,842 Cook May 23, 1939 1,315,614 True Sept. 9, 1919 2,116,562 Cruser May 10, 1938 2,293,455 Disch et al. Aug. 18, 1942 

